Variable condenser



F. B. NEWELL Feb. 4, 1930;

VARIABLE CONDENSER Filed Dec. 10, 1923 i l M IAVEA TOR @1 1; :4/650 fig/ 7 7 4 TTORNE Y Patented Feb. 4, 1930 UNITED STATES FLOYD B. NEWELL, OF DAYTON, OHIO VARIABLE CONDENSER Application filed December 10, 1923.

This invention relates to variable condensers of the type in use in radio communication. One object of the invention is to provide a condenser with means for obtaining fine changes in the capacity of the same.

A second object is to provide a condenser of this character in which the fine changes are obtained by the movement of di-electric plates so as to be inserted to a greater or a less extent between the superposed conducting plates so as to displace the main dielectric therebetween.

Further objects will be more fully set forth in the attached specification and claims, and

in the drawings, in which:

Fig. 1 is a plan view of a condenser embodying my invention, and

Fig. 2 is a side elevation of the same.

The condenser is shown as having a set of spaced fixed conducting plates 10 of semi-circular construction and a movable set of semicircular conducting plates 11, the plates 10 and 11 being interleaved in the customary manner. The movable plates 11 are adapted to be adjusted about an axis 12 by means of the adjusting knob 13, and the fixed plates are held by the cylindrical spaced members 14 in fixed position between the upper cover plate 15 and the lower base plate 16, and electrical connections 17 and 18 are connected to the set of "movable plates and to the set of stationary plates, respectively.

In order to provide a fine adjustment of the capacity of the condenser, I provide a 0.) series of segmental plates 19 suitably mounted upon a rod 20 so as to be adjustable about an axis 21 by means of the adjusting knob 22. These plates 19 are not electrically connected to the rest of the electrical circuit but are provided so as to-displace the main dielectric, which in this case is air, between the plates 10 and 11 to an suitable extent. The plates 19 are preferably formed of an insulating material having a different coeflicient from the air or the main dielectric used. Very fine changes in the capacity may therefore be obtained after an approximately correct adjustment of the condenser has been eflected b means of the adjusting knob 13, by simply adjusting the plates 19 about the axis 21. As

. comparatively small.

Serial No. 679,753.

an increasing amount of the plates 19 is caused to be inserted between overlapping portions of the superposed plates 10 and 11, corresponding changes in the capacity of the condenser are efi'ected which are however, of a very small nature, as the change in the dielectric between these portions of the plates is The rod forming the axis 21 upon which the plates 19 are mounted, and the adjusting knob 22 are preferably constructed of an insulating material, and as the plates 19 themselves are in'no way electrically connected to the conducting portions of the circuit, it will be seen that there will be a smaller tendency to cause a change in the capacity of the condenser by the proximity of the hand of the user or by the removal of the users hand after adjustments have been made. The location of the adjusting knob 22 at the end of the apparatus as shown is especially desirable for this reason, that is, so as small changes in the capacity of the condenser by the withdrawal of the hand is prevented after adjustments have been made. With the adjusting knob 22 in the position shown, it is not necessary for the hand to come as close to the center of the plates in effecting adjustments as would otherwise be required.

1. A variable condenser for use in radio communication comprising a set of stationary plates, a set of movable plates spaced from and alternated with the stationary plates, means for manually moving said movable plates to vary the capacity of the condenser agid insulator means bisecting the dielectric space between said stationary and movable plates for creating a fine adjustment of the capacity between the stationary plates and the movable plates-while the said movable 9 plates are maintained in their adjusted position relative to the stationary plates.

2. A variable condenser for radio circuits comprising a set of stationary metallic plates, a set of movable metallic plates to be interposed between said stationary plates in variy able relation thereto, and an insulator plate manually operable between one of said stationary plates and one of said movable plates "stationary conducting plates, a set of spaced movable conducting plates, adjustable between said stationary lates, said plates having a main dielectric etween the same, and

a plate having a different dielectric constant than the main dielectric to displace the main dielectric by adjustment between the plates.

5. A variable condenser comprising segmental conducting plates stationarily mounted, segmental conducting plates movable in spaced relation between said stationary plates on an axis, and a segmental insulator plate mounted to turn on an axis outside the path of said movable plates to move to various po-' sitions between one of said movable plates and one of said" stationary plates.

-6. A variable condenser comprising segmental conducting'plates stationarily mounted, segmental conducting plates movable in spacedrelation between said stationary plates on an axis, and a segmental insulator plate mounted to turn on an axis outside the path of said movable plates to move to various positions between one of said movable plates and one of said stationary plates to cause fine adjustments of the capacity of the condenser,

and means formed of insulating material for..

supporting and moving said insulator plate. The combination with a variable radio condenser having relatively movable metallicplates adjustable to vary the capacity of the condenser, of an auxiliary member of insulating material movable independently of said metallic plates and insertable therebetween to vary the dielectric value of the condenser and thereby effect afine adjustment of the capacity; v

8. In a radio condenser, the combination with relativel movable metallic plates of a.

' plate of insu ating material movable independently of said metallic plates and insertcent plates being insulated from each other 7 and alternate plates connected together and movable bodily with respect to the remaining plates, of a movable member having a dielectric value other than unity adapted to be interposed between said first plates to vary the dielectric strength and hence the capacity of the condenser.

11. Ina radio condenser the combination with opposed spaced metallic plates, adjacent plates being insulated from each other and alternate lates connected together, of means for hol ing said plates in fixed position relative to each other, a rotatable shaft at one side of said plates and a member of .a substance having a dielectric value other than unity secured to said shaft and adapted upon rotation of the same to be inserted more or less between adjacent plates.

'12. In a radio condenser the combination with opposed spaced m'etallic plates, adjacent plates being insulated from each other and alternate dplates connected to ether, of means for hol ing said plates in xed posi tion relative to each other, a rotatable shaft journaled at one side ofsaid plates, and a thin plate of insulating material having a dielectric value other than unity carried by said shaft and adapted to be inserted to varying degrees between said plates upon rotation thereof, said plate having at its margin an elongated tapering point to render the variation of dielectric value gradual.

13. In a variable radio condenser, having fixed and movable metallic plates, a dielectric member movable independently of said plates to vary minutely the capacity as determined by the relative positions of said plates.

14. An attachment for variable radio con-- densers of the type having two sets of metallic plates movable relatively toeach other to vary the capacity, said attachment comprising a plate of insulating material adapted to be inserted to a variable extent between certain of said first plates, a member for supporting and moving said last plate, and means for securing said member in operative relation to said condenser.

FLOYD B. NEVVELL.

able therebetween to vary the dielectric value of the condenser and thereby effect a fine adjustment of the capacity.

.9. In a variable condenser, the combination with metallic plates movable relatively to each other of a member of material having a dielectric value other than unity and means for inserting said member more or less between adjacent metallic plates to 'vary the dielectric value of the condenser.

' 10. In a radio condenser the combination with opposed spaced metallic plates.' adja- 

